1. Technical Field
This invention relates to backlighting, and more particularly, to a backlight display having solderless terminals.
2. Related Art
Some liquid crystal displays are lighter, smaller, and consume less power than conventional monitors. The liquid crystal displays include a liquid crystal display panel having liquid crystal cells positioned between two substrates. An illuminating unit may be positioned behind the liquid crystal display panel to supplement light received from external sources. An edge type or direct type illuminating display may improve clarity and brighten the display panel.
In some edge type displays, a lamp, a light guide, and a reflecting plate transmit light to the liquid crystal display panel with minimal attenuation or loss. The light guide receives light from the reflecting plate and the lamp positioned near the peripheral edge of the liquid crystal display panel. In a direct type display, multiple lamps are positioned between the peripheral sides of the liquid crystal display panel below a light spreading means. Direct type displays can be very efficient and produce a high brightness. These displays may be used in large liquid crystal displays.
While direct type displays can be more efficient than other conventional displays, the direct type displays can be susceptible to lamp failure. When one or more lamps fail in a direct type display, a portion of the liquid crystal display panel may not illuminate leaving that portion darker than the rest of the display panel. In a similar edge type display, a lamp failure may be less noticeable as the light guide can compensate for the uneven brightness.
Since a lamp failure can be more noticeable in direct type displays, the burned out lamps often require replacement. In a direct type liquid crystal display (LCD), a mounting and disconnecting structure is often used. The mounting and disconnecting structure may include a fusible tin and lead alloy such as solder that joins metallic parts together.
FIGS. 1 and 2 illustrate a direct type display that includes a plurality of lamps 1 having electrodes 2 positioned at opposite ends of the lamp tubes. A lower frame 3 underlies a bottom portion of the lamps 1 terminating at an upper frame 6 that receives the lamp tube ends. A reflective plate 4 directs light from the lower frame 3 that couples a plurality of lamp holders 5. In the direct type display of FIG. 2, lamps 1 electrically couple a power source through a plurality of electrodes 2 positioned at opposite ends of the lamps 1. The inner lead lines 7 electrically couple a contraction tube through a fusible tin and lead alloy such as solder. The outer lead lines are held/connected to inverters (not shown) by wires 10 positioned near an underside of the lower frame 3.
The soldering process joins the inner lead line 7 and the outer lead line 10. The expansion and contraction of the direct type display or the external force (particularly, a bending force) needed to insert the tubes may cause an immediate or latent failure of the solder joints. The forces and vibrations induced through the transportation and handling of the direct type displays may also induce stress, which must be absorbed by the components and the solder joints causing internal damage.
FIGS. 3 and 4 illustrates another backlight unit having a plurality of lamps 31 and an outer case 33 placed under light spreading means 35a, 35b, and 35c. The light spreading means 35a, 35b, and 35c includes a plurality of diffusion sheets and diffusion plates positioned above the lamps. A reflective plate 37 is positioned below the lamps to direct light toward the display. Like FIG. 2, the lamps are lamp tubes having electrodes 32 positioned at opposite ends of the lamp tubes. Lead lines 39 and 39a are connected to the electrodes 32 to provide power to the backlight assembly. Each of the lead lines 39 and 39a of a particular lamp tube are connected to a driving circuit through a separate connector. The lead lines 39 and 39a are electrically connected to the electrodes 32 and a voltage source through a solder joint. Other solder joints 40 connect one of the lead lines 39 or 39a to the outer case.
Like many solder joints, the stress caused by movement and the difficulty in forming a solder joint can result in latent, and a catastrophic joint failure. The embodiments overcome some of these potential drawbacks in the related art.